The state of Gareth Barry's ankle makes an unlikely cause célèbre. The injury of choice for England's key players used to be the fractured metatarsal, the front pages of national newspapers transformed into makeshift prayer mats through which readers could transfer positive energy to the likes of David Beckham and Wayne Rooney to speed their recovery. Barry lacks the on-pitch charisma or effervescence of either, yet he has become this team's key component.

Fabio Capello surveyed Monday's friendly against Mexico and, even in victory, departed perturbed at the prospect of being denied a player upon whom he has come to rely. Barry does not snap into challenges like Claude Makelele in his pomp, or intimidate the opposition into shrinking away as Patrick Vieira once did. Yet he is quietly and busily efficient both at harassing his markers into relinquishing possession and, critically, in shifting the ball on to a team-mate to give England their rhythm. The 29-year-old has featured in 19 of Capello's 23 games in charge. No wonder the manager will give him every opportunity to prove he can play his part at the World Cup.

The manager's principal fear is that, with Owen Hargreaves's season having amounted to 35 seconds as a substitute for Manchester United, he appears to have no real viable alternative to Barry, particularly as he is loth to depart from his favoured variations of 4-2-3-1.

The Manchester City midfielder is generally disciplined, reliable and steady with his passing. Michael Carrick should offer something similar, even if his more languid style contrasts with his team-mate's scuttling energy, yet he fluffed his lines so horribly against the Mexicans that he no longer feels like a natural replacement in waiting. That must arguably have been Capello's biggest disappointment in a sloppy display where possession was dominated by Mexico and alarming space was prised out between England's rearguard and defensive midfield line.

Carrick is capable of so much more, but his passing was awry, his tempo when pressing somewhat slack and his confidence apparently fragile. There was no presence and little authority. He ended up bypassed and, increasingly, anonymous.

James Milner, at his side in the first half, cannot match Carrick's experience at this level and seemed too eager to maraud forward, often to the cost of his partner in the centre and the exposed left-back, Leighton Baines, leaving pockets of space into which the Mexicans' fluid midfield poured.

"When you face a team who are so comfortable on the ball and have got good movement, then it becomes a snowball effect," said the centre-back Ledley King, who was left equally unprotected with no obvious midfield shield ahead of him. "One player can't get tight enough, then they pop the ball off and the next player's in between [the lines]. That happened too many times."

Capello defended Carrick, whose reputation admittedly should not be damned on the basis of one slack display. "He has had some good games with us, but our performance was not down to one player," he said. "The performance was down to the team, not one player." Yet the Manchester United midfielder has appeared off-colour for some time, primarily for his club. Barry might at least have disrupted the opponents' authority in that no man's land between defence and midfield. Without him, Englandappeared vulnerable.

Steven Gerrard, hauled in from the left for the second half as he and Milner swapped positions, did offer some forward-thinking purpose and thrust which unnerved the visitors. But, on the assumption that Frank Lampard will be one of the two central players selected against the USA on 12 June, Capello is not inclined to play the Liverpool captain in such a deep-lying role, although he could end up with little choice.

"They both want to go forward but, if you lose the ball near the box, there is the danger of a counter-attack," the Italian said. "Steven is really dangerous when he arrives close to the [opponents'] box and I prefer him to be there. Maybe you always need a holding player in front of the back four. This position is really important."

On that basis, Tom Huddlestone – granted a second cap on Monday, albeit he was on the pitch for less than half an hour – may be considered, though his lack of experience and speed on the turn may be prohibitive. Scott Parker, yet to kick a ball for Capello, is another who enjoys galloping forward, leaving the management potentially to consider such players as Jamie Carragher and King, veteran centre-halves who have each played in midfield on demand for England.

But neither seems the natural fit, both lacking the pace to recover if bypassed, and their inclusion in the role might demand an entire change of system. "A lot has changed since I last played there," King said with admirable honesty. "Given that I don't train, midfield is a very different role and different on the body. I have got used to playing at the back and adapting to certain, familiar movements. Midfield would be totally different."

He did add that he would be "willing to try it" if required, though it has not quite come to that. Not, at least, while Capello still holds out some hope for Barry's recovery. It may be time for the Italian to reach for his prayer mat after all.